U.S. patent application number 12/441753 was filed with the patent office on 2009-12-03 for device for the weld joining of sheet metal strips.
This patent application is currently assigned to SIEMENS VAI METALS TECHNOLOGIES SAS. Invention is credited to Stephane Barjon, Jean Perret, Herve Thomasson.
Application Number | 20090294418 12/441753 |
Document ID | / |
Family ID | 37951733 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090294418 |
Kind Code |
A1 |
Barjon; Stephane ; et
al. |
December 3, 2009 |
Device for the Weld Joining of Sheet Metal Strips
Abstract
A device for the laser weld joining of sheet metal strips
includes the following elements: a main frame, a laser welding unit
including a laser beam generator for welding the sheet metal strips
to be joined and a welding head, a clamping jaw unit supported by
the frame and used to clamp the sheet metal strips, and a shearing
unit for shearing the head and tails of the sheet metal strips to
be joined. The shearing unit includes upper blades mounted to a
blade holder and lower blades which can move in relation to the
upper blades and which are designed to shear a strip, as well as a
blade connecting structure fixed to the frame, the above-mentioned
welding head being mobile between the blade holder and the lower
blades.
Inventors: |
Barjon; Stephane; (Montrond
les Bains, FR) ; Thomasson; Herve; (Seyssuel, FR)
; Perret; Jean; (Essertines-en-Chatelneuf, FR) |
Correspondence
Address: |
LERNER GREENBERG STEMER LLP
P O BOX 2480
HOLLYWOOD
FL
33022-2480
US
|
Assignee: |
SIEMENS VAI METALS TECHNOLOGIES
SAS
Saint-chamond
FR
|
Family ID: |
37951733 |
Appl. No.: |
12/441753 |
Filed: |
August 8, 2007 |
PCT Filed: |
August 8, 2007 |
PCT NO: |
PCT/FR07/01355 |
371 Date: |
April 16, 2009 |
Current U.S.
Class: |
219/121.64 ;
219/121.63 |
Current CPC
Class: |
B23D 15/08 20130101;
B23K 26/26 20130101 |
Class at
Publication: |
219/121.64 ;
219/121.63 |
International
Class: |
B23K 26/20 20060101
B23K026/20 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2006 |
FR |
0 608 349 |
Claims
1-14. (canceled)
15. A device for laser weld joining of sheet metal strips running
in a steelworks of continuous processing, comprising: a main frame;
a clamping unit carried by said main frame for clamping sheet metal
strips, said clamping unit including first and second clamps each
configured to clamp a respective sheet metal strip; a shearing unit
for shearing heads and tails of sheet metal strips to be joined,
said shearing unit including: an upper blade holder, first and
second upper blades fastened on said upper blade holder in spaced
relation with one another; first and second lower blades moving
relative to said upper blades and adapted to shear a sheet metal
strip; at least one joint structure of said first blades, said
joint structure being in fixed relation to said frame; a laser
welding unit including a generator for a laser beam for welding the
sheet metal strips to be joined and including a welding head
slidably mounted for moving in a space located between said upper
blade holder and said lower blades.
16. The device according to claim 15, wherein said first blades are
movably disposed for movement between said first and second
clamps.
17. The device according to claim 15, wherein said joint structure
comprises two posts in fixed relation to said main frame and a beam
extending between said posts, and wherein at least one of said
upper blades is supported by said beam.
18. The device according to claim 17, wherein said joint structure
comprises shearing jacks supported by said beam for moving said
first and second upper blades relative to said first and second
lower blades.
19. The device according to claim 15, wherein said upper blades and
said lower blades are mounted for moving in order to adopt a
position of penetration of said upper blades and lower blades
wherein said first lower and upper blades are a first blade
clearance apart and wherein said second lower and upper blades are
a second blade clearance apart, and further comprising mechanical
operating means adapted to vary said first and second blade
clearances under control of an electronic system for blade
clearance control.
20. The device according to claim 19, wherein said mechanical
operating means are configured to move said lower blades relative
to one another for varying said first and second blade
clearances.
21. The device according to claim 19, wherein said electronic
system comprises data collection means adapted to gather and
collect data specific to the sheet metal strip to shear and adapted
to vary said blade clearances automatically in dependence on the
data thus collected.
22. The device according to claim 15, wherein said laser welding
unit comprises a gooseneck-shaped structure mounted for translation
relative to said frame and carrying said welding head.
23. The device according to claim 17, wherein said laser welding
unit comprises a gooseneck-shaped structure mounted for translation
relative to said frame and carrying said welding head, and wherein
at least one of said posts is formed with a cut-out crossing the
post and at least a part of said gooseneck-shaped structure
carrying said welding head is disposed inside said cut-out, in
order to cross said post and to be able to slide therein.
24. The device according to claim 22, wherein said welding head is
mounted for sliding relative to said gooseneck-shaped structure
through a system of guides.
25. The device according to claim 15, wherein said first and second
clamps are disposed in spaced relation with one another and said
clamping unit comprises mechanical linking means of said clamps to
said main frame adapted to move said first and second clamps from
one another and relative to said main frame.
26. A method for laser weld joining of sheet metal strips running
in a steelworks of continuous processing, which comprises: holding
a tail of a sheet metal strip to be joined with a first clamp and
holding a head of a sheet metal strip to be joined with a second
clamp; shearing the head and the tail of the sheet metal strips
with a shearing unit; subsequently moving the sheet metal strips so
sheared closer together; and subsequently welding with a laser
beam; and thereby performing the shearing step, the moving step,
and the welding step without releasing the clamps.
27. The method according to claim 26, wherein: the shearing step is
performed with a shearing unit having an upper blade holder with
first and second upper blades fastened to the upper blade holder in
spaced relationship and having first and second lower blades moving
relative to the upper blades and adapted to shear a sheet metal
strip; the shearing unit comprises at least a joint structure of
the first blades, the joint structure being fixed relative to a
frame; and the shearing step comprises simultaneously bringing
closer together the upper blades, carried by the upper blades
holder, and the lower blades.
28. The method according to claim 27, which comprises welding with
a welding head moving within a space located between the upper
blade holder and the lower blades, and wherein the blades are
disposed to be moved between the first and second clamps.
Description
[0001] The present invention relates, generally speaking, to the
field of the devices for the butt welding of two sheet metal strips
by means of a Laser beam. This invention is particularly suited to
the welding performed for the joining together of sheet metal coils
at the entry of the sheet metals continuous conveyer line in the
steel industry.
[0002] More particularly, the invention relates to a device for
Laser weld joining of sheet metal strips running in a steel-works
of continuous processing comprising at least: [0003] a main frame;
[0004] a Laser welding unit comprising a generator of Laser beam
for the welding of sheet metal strips to join; [0005] a clamps unit
carried by said frame for the clamping of sheet metal strips;
[0006] a shearing unit (C) for the shearing of heads and tails of
sheet metal strips to join;
[0007] The lines of production, of transformation and of coating of
steels are today designed for a continuous processing often linking
up several successive processings without intermediate steps in
order to improve steelworks productivity.
[0008] To do that, it is often necessary to butt weld two sheet
metals in order to get a sheet metal strip without discontinuity
capable of running in the steel conveyer line. To do that, one
therefore weld joins a tail of a sheet metal strip inserted on the
conveyer line with the head of another strip known as next
strip.
[0009] The running of the strip having to remain continuous on the
whole set of the conveyer line and the joining being realized in a
fixed position, the continuous conveyer lines comprise devices that
accumulate the strip by multiple loopings during the joining then
return it. Such an accumulation device of this type is described in
patent EP 0 974 408.
[0010] The joining operation is realized by a welder that
comprises, in addition to the welding device in itself (butt weld
by flashing, by electrode wheel, by metal inert gas, by Laser) two
clamps for immobilizing the sheet metals, one located downstream by
comparison with the sheet metal strip running direction and for
immobilizing the coil tail already inserted in the conveyer line,
the other being located upstream in order to selectively immobilize
the head of the coil that has just been inserted.
[0011] These welders must be capable of making butt joints of high
quality. As, indeed, the breaking of a weld during the running of
the sheet metal strip or even the necessity to redo a weld
considered incorrect cause important operating losses and the rate
of breaking or of re-welding must stay as low as possible.
[0012] The decisive criteria of a weld quality essentially are:
[0013] the metallurgical quality of the welded butt joint,
particularly for steels sensitive to possible metallurgical
deteriorations of the area affected thermally by the welding;
[0014] the welded section that should ideally be without extra
thickness and under-thickness; [0015] the continuity and
compactness of the welded butt joint.
[0016] The metallurgical quality depends also on the welding
process used and on the thermal cycle induced by this process in
the affected area, as well as on various processes of pre- and
post-heating or of annealing made locally in the welder itself or
immediately downstream.
[0017] The state of the welded section depends on the process and
on the means of finishing implemented after welding. The butt
welding by flashing makes an overlap which is necessary to plane
and the welders by flashing known in the field as "flash-butt" are
in general equipped with an embedded planning unit. The welding by
electrode wheel also makes an extra thickness due to the
overlapping of the sheet metals to weld and that most often has to
be squeezed by ironing roll devices embedded in the welders. The
Laser welding enables a sharp management of the welded section
furthermore associated with a very limited area affected by the
heat.
[0018] The continuity and the compactness of the butt joint are
essentially depending on the welding parameters used. For the most
part, these parameters are electrical and are generally easy to
manage in a reliable fashion.
[0019] Another parameter however is of prime importance for the
continuity and the compactness of the welded butt joint as much as
for its section, namely the straightness of the edges to weld and
their relative positioning during the welding.
[0020] In order to ensure the joining weld quality, the ends of the
strips to weld need to be aligned and straight. To do that, the
joining assemblies comprise various centring devices upstream and
downstream from the welder that enable to align the sheet metal
strips and means of shearing of the heads and tails of the sheet
metal strips.
[0021] Thus the welders generally comprise means of shearing
enabling to make the cutting of the ends of the strips to join. The
considerable range extension of metal types and of thickness of
steel processed in the continuous conveyer lines and the constantly
strengthened productivity requirements have been directing for 20
years the in-line joining welders towards the Laser process.
[0022] The Laser process indeed enables to extend the range of
products (sheet metals to weld) towards very small thicknesses. It
also enables to limit the thermally affected areas of a very wide
range of metal types among which can be counted special metallurgy
steels designed for the automotive industry.
[0023] Historically, the Laser welders have been designed based on
welder architectures of the above-mentioned "flash-butt" type and
of electrode wheel type they were intending to replace. The systems
of shearing of the heads and tails of strips are off-line of sheer
metal strips conveyer line, and are installed on gooseneck-shaped
brackets that are inserted in the welder frame to make the two
cuttings then are put back off-line in order to make room for the
welding operation.
[0024] Such a shearing system used jointly with the Laser process
is described as far back as 1984 in patent document U.S. Pat. No.
4,626,651.
[0025] A joining device of the type previously defined, enabling
such a weld joining of sheet metal strips, is described for example
in the patent document EP 1 157 753. This device of prior art which
is described in FIG. 1 is supplied with a welding unit 4 in a fixed
position by comparison with the main frame 1 and thus by comparison
with an axis "A" of running of the sheet metal strips. This welding
unit 4 comprises a generator of Laser beam 45. This device 0 also
comprises a shearing unit C moving by comparison with the main
frame 1 in order to make the size of the gap between the shearing
unit C and the main frame 1 vary, the shearing unit thus being
moving between a shearing position wherein the shearing unit C is
centred on the strip running axis "A" and a standing back position
wherein the shearing unit C is off-centred by comparison with said
axis.
[0026] In this context, the present invention is aiming at
providing a joining device enabling to improve the precision of
joining of sheet metal strips so as to allow weld homogeneity and
so as to reduce for example the risks of stopping of the sheet
metal strips running because of weld breaking.
[0027] To that purpose, the device for Laser weld joining of sheet
metal strips of the invention, besides in accordance with the
generic definition given by the preamble defined previously, is
essentially characterized in that the shearing unit comprises at
least a first upper blade and at least a first lower blade moving
from one another and adapted to shear a sheet metal strip and in
that the shearing unit comprises at least a joint structure of said
first blades, this joint structure being in fixed relation to said
frame.
[0028] The invention enables an improvement of precision and of
repetitiveness of the cuttings of the shearing unit which is in a
fixed position by comparison with the device frame (that is to say
fixed by comparison with the frame) thanks to the joint structure
of said first blades that is in a fixed relation with said
frame.
[0029] Thanks to this improvement of the quality of shearing of the
sheet metal strips edges, these strips can directly be Laser welded
without necessarily need means of measurement and of correction of
the position of the strips ends.
[0030] Thanks to this improvement of the cuttings precision, the
invention enables to simplify the process of joining the sheet
metal strips because it is not necessarily needed anymore to
reposition the sheared sheet metal strips from one another to make
them parallel to one another before welding them.
[0031] To this same purpose, the invention also relates to a device
for Laser weld joining of sheet metal strips running in a
steelworks of continuous processing comprising at least: [0032] a
main frame; [0033] a Laser welding unit comprising a generator of
Laser beam for the welding of sheet metal strips to join; [0034] a
clamps unit carried by said frame for the clamping of sheet metal
strips, this clamps unit comprising first and second clamps each
adapted to the clamping of a sheet metal strip; [0035] a shearing
unit for the shearing of heads and tails of sheet metal strips to
join.
[0036] This device of the invention being characterized in that the
shearing unit comprises an upper blades holder, of first and second
upper blades fastened on said upper blades holder in order to be in
spaced relation with one another, and of first and second lower
blades moving by comparison with the upper blades and adapted to
shear a sheet metal strip, the shearing unit comprising at least a
joint structure of said first blades, this joint structure being in
fixed relation to said frame and the welding unit furthermore
comprising a welding head mounted for sliding in order to be able
to move in a space located between the upper blades holder.
[0037] The fact of having upper blades carried by the same blades
holder enables to fasten these upper blades from one another which
improves the precision of each cutting of strips made by the upper
blades so as the precision of relative positioning of the cuttings.
The outcome of it is an improvement of the quality of welding of
the strips thus precisely cut.
[0038] The fact that the upper blades holder and the lower blades
are linked together through the joint structure fixed to the frame
also improves the precision of the cuttings.
[0039] The fact that the welding head can be moved between the
upper blades holder and the lower blades also enables to improve
the positioning precision of this head by comparison with the upper
blades holder and consequently to improve the positioning precision
of the Laser beam directed by the welding head to the edges of
strips cut beforehand by the blades.
[0040] Overall this combination of characteristics enables to
improve the quality of the weld by allowing a precision of cutting
and of positioning of the sheet metal edges by comparison with the
Laser beam.
[0041] Preferably the lower and upper blades are disposed to be
moving between said first and second clamps.
[0042] One can see for example that the shearing unit furthermore
comprises: [0043] a second upper blade in spaced relation with the
first upper blade, these upper blades being in fixed relation with
one another; [0044] a second lower blade in spaced relation with
the first lower blade, these lower blades being in fixed relation
with one another, the second blades being moving from one another
and being adapted to shear a sheet metal strip.
[0045] This embodiment enables to cut two sheet metal strips
simultaneously, which allows a saving of time in the operation of
shearing/cutting.
[0046] Preferably the upper and lower blades are parallel to one
another, the first blades being sliding along and on both sides of
a first shearing plane and the second blades being sliding along
and on both sides of a second shearing plane.
[0047] This parallelism between blades enables to obtain cuttings
of the edges of the sheet metal strips parallel to one another, as
it happens these cuttings are a cutting of a tail of a sheet metal
and a cutting of a head of another sheet metal. This blades
parallelism also enables to ease the welding because the ends to
weld are cut parallel to one another and can thus be brought closer
to one another while keeping an inter-sheet metals gap controlled
and relatively constant along the whole width of the sheet metals
(that is to say along the cuttings) which allows to obtain a
homogeneous weld.
[0048] To that purpose the lower blades are preferably mounted on a
lower tool holder support shared by the lower blades, and the upper
blades are preferably mounted on an upper blades holder also called
upper tool holder support shared by the upper blades.
[0049] One can see for example that the clamps unit comprises first
and second clamps each adapted to the clamping of a sheet metal
strip and that said blades are disposed to be moving between said
first and second clamps.
[0050] In this embodiment the shearing planes are located between
the first and second clamps.
[0051] One can see for example that said joint structure comprises
two posts in fixed relation to said main frame and a beam extending
between these posts, said at least one upper blade being supported
through said beam.
[0052] This embodiment is advantageous because the posts linked
together by a beam are forming a joint structure of the blades
rigid in comparison to the rigidity of a gooseneck-shaped structure
for example.
[0053] This increased rigidity of the joint structure of the blades
is thus in favour of a precision of blades positioning all along
the shearing stress. This advantage will be further described by
reference to FIG. 6 which compares a shearing unit comprising a
gooseneck-shaped joint structure to a joint unit supplied with two
posts linked by a beam.
[0054] One can see for example that said joint structure comprises
shearing jacks supported by said beam to move said first and second
upper blades by comparison with said first and second lower
blades.
[0055] This embodiment enables to focus the cutting stress on the
beam that is a rigid place of the joint structure which thus
improves the cutting quality.
[0056] One can see for example that said upper and lower blades are
mounted for moving in order to adopt a position of penetration of
said upper and lower blades wherein the first lower and upper
blades are a first blade clearance apart and wherein the second
lower and upper blades are a second blade clearance apart, the
device furthermore comprising mechanical operating means adapted to
make said first and second blade clearances vary due to the effect
of an electronic system of control of blade clearance.
[0057] The use of mechanical means of operating disposed to make
the blade clearances vary according to a command coming from an
electronic system of control of blade clearance is particularly
advantageous because it enables to have a cutting quality
adjustable by modification of the blade clearances.
[0058] These blade clearances are chosen according to
characteristics of the sheet metal strips to shear.
[0059] One can see preferably that said mechanical means of
operating are adapted to move said lower blades from one another
and thus to make said first and second blade clearances vary.
[0060] Preferably the electronic system of control comprises means
of data collection means adapted to gather data specific to the
sheet metal strip to shear and adapted to make automatically said
blade clearances vary thanks to said means of operating according
to said collected data.
[0061] Those data are for example the thickness of the sheet metal,
its width, its hardness.
[0062] One can see for example that the Laser welding unit
comprises a gooseneck-shaped structure mounted for translation by
comparison with said frame and a welding head carried by the
gooseneck-shaped structure.
[0063] This gooseneck-shaped structure has rigidity sufficient to
stand welding stresses and thus enables the moving of the welding
head opposite the areas of strips to weld while reducing the
guiding inaccuracies of the welding head.
[0064] One can see for example that at least one of the posts
comprises a cut-out crossing this post and that at least a part of
said gooseneck-shaped structure carrying the welding head is
disposed inside this cut-out in order to cross this post and to be
able to slide in it.
[0065] This embodiment enables to position the gooseneck-shaped
structure in an area of the device of the invention relatively
rigid and that cannot be much distorted which is the area close to
the upper blade(s) support beam. This embodiment is advantageous
because it reduces the risk of distorsion of the device under the
stresses produced during the welding and thus improves the
homogeneity of the weld.
[0066] One can see for example that the welding head is mounted for
sliding by comparison with the gooseneck-shaped structure through a
system of guides.
[0067] This embodiment enables to move the welding head to make the
welding without having to move the gooseneck-shaped structure that
is relatively heavy in comparison to the welding head, this
embodiment allows to control the feeding speed of the welding
head.
[0068] One can see for example that the device of the invention
comprises first and second guide rollers mechanically linked to the
welding head in order to be moving, by motion of translation, with
this welding head, the mechanical link of first and second guide
rollers being adapted to position the first guide roller opposite a
first side of a clamp of the clamps unit and to position the second
guide roller opposite a second side of a clamp of the clamps unit,
each of these guide rollers being adapted to press a sheet metal
strip against the clamp side opposite which it is positioned.
[0069] This embodiment is advantageous because it enables to limit
the positioning scatterings of the welding head by comparison with
the edges of the sheet metal strips to weld which is in favour of
the homogeneity of the weld thus obtained.
[0070] One can see for example that the mechanical link of the
first and second guide rollers comprises at least a hydraulic jack
adapted to bring closer and move away the first and second guide
rollers to/from the respective first and second clamp sides.
[0071] One can see for example that the clamps unit comprises first
and second clamps in spaced relation with one another and
mechanical means of linkage of the clamps to said main frame, these
means of linkage of the clamps to said main frame being adapted to
move said first and second clamps from one another and by
comparison with the main frame.
[0072] This embodiment enables to bring closer together and to
position the sheet metal strips after having them cut without
having to release the clamps. The outcome of it is a saving of time
and a precision improvement in the joining process.
[0073] One can see for example that said first clamp has a lower
claw and an upper claw and that one of these claws of first clamp
is shorter than the other in order to enable, during the shearing
of a sheet metal strip, the passing of one of said blades, this
blade thus being adapted to be disposed in a position of
compression of said sheared sheet metal strip against the largest
claw of the first clamp.
[0074] This embodiment is advantageous because the blades are thus
positioned the closest possible to the clamps which limits the size
of the gap between a shearing plane of a sheet metal and the clamp
carrying this sheet metal.
[0075] One can see for example that said second clamp has a lower
claw and an upper claw and that one of these claws of the second
clamp is shorter than the other in order to enable, during the
shearing of a sheet metal strip, the passing of one of said blades,
this blade thus being adapted to be disposed in a position of
compression of said sheared sheet metal strip against the largest
claw of the first clamp.
[0076] This embodiment is complementary to the previous one and
presents the same advantages.
[0077] One can see for example that the device of the invention
comprises a retractable stop moving between an up position wherein
this retractable stop is disposed in a space located between the
clamps of the clamps unit and a down position wherein this stop is
away from the space located between the first and second
clamps.
[0078] This retractable stop in down position is outside a sheet
metal strip running plane in order for this sheet metal strip to
run freely in the shearing unit.
[0079] In up position, this retractable stop which extends between
the clamps is then useful: [0080] to be used in the positioning of
a first sheet metal strip held in the first clamp by comparison
with the first blades; and [0081] to be used in the positioning of
a second sheet metal strip held in the second clamp by comparison
with the second blades.
[0082] Indeed when the stop is in up position it can then be used
to butt the tail of a first sheet metal strip and the head of the
second sheet metal strip and thus position them by comparison with
the shearing unit and thus with the main frame. This retractable
stop belongs preferably to the shearing unit and extends preferably
between sliding planes of the first and second blades.
[0083] The invention relates as well to a process of control of the
device of the invention according to anyone of the embodiments
above-mentioned, characterized in that a tail of a sheet metal
strip to join is held thanks to a first clamp and a head of a sheet
metal strip to join is held thanks to a second clamp, then the head
and the tail of said sheet metal strips are sheared thanks to said
shearing unit, then the sheet metal strips thus sheared are brought
closer together and positioned and they are welded thanks to a
Laser beam, these operations of shearing, of bringing closer, of
positioning and of welding being realized without releasing the
clamps.
[0084] The invention relates also to a process of Laser weld
joining of sheet metals strips running in a processing steelworks,
characterized in that a tail of a sheet metal strip to join is held
thanks to a first clamp and a head of a sheet metal strip to join
is held thanks to a second clamp, then the head and the tail of
said sheet metal strips are sheared thanks to a shearing unit, then
the sheet metal strips thus sheared are brought closer together and
positioned and they are welded thanks to a Laser beam, these
operations of shearing, of bringing closer, of positioning and of
welding being realized without releasing the clamps.
[0085] The processes according to the invention enable to improve
the weld quality because they allow to avoid inaccuracies that are
normally generated by repositionings of strips during repeated
operations of clamping/releasing.
[0086] Preferably for the implementation of the joining process of
the invention, one see that the shearing unit used for the shearing
operation comprises an upper blades holder, of first and second
upper blades fastened on the upper blades holder in order to be in
spaced relation with one another and from the first and second
lower blades moving by comparison with the upper blades and adapted
to shear a sheet metal strip, on the other hand one see that the
shearing unit comprises at least a joint structure of said first
blades, this joint structure being in fixed relation with said
frame, and one realizes the shearing operation by simultaneously
bringing closer the upper blades carried by the upper blades holder
to the lower blades.
[0087] This embodiment enables to limit the uncertainties of
relative positioning of the cuttings because: [0088] on one hand
the cuttings of tail and head of the strips are respectively
realized simultaneously by blades in fixed relation with one
another mounted on the blades holder which balances the cutting
stresses; and [0089] on the other hand the upper and lower blades
are linked together through the joint structure in fixed relation
with said frame.
[0090] For the implementation of the joining process of the
invention, one see that the welding is realized thanks to a welding
head moving in a space located between the upper blades holder and
the lower blades, said blades being disposed in order to be moving
between said first and second clamps.
[0091] The fact of moving a welding head between the upper blades
holder and the lower blades enables to make the welding directly
between the upper and lower blades without being forced to move the
head and tail of strips out of the interblades gap. The outcome of
it is a saving of time, of space and an improvement of the
precision because the moving of the sheared head and tail of sheet
metals is reduced to a minimum.
[0092] Preferably for the implementation of the Laser weld joining
process of the invention, one can see that the welding is made
thanks to a welding head moving in a space located between the
upper blades holder and the lower blades, said blades being
disposed in order to be moving between said first and second
clamps.
[0093] Preferably this space for the moving of the welding head is
designed to exist only when the upper blades holder and the lower
blades are at least a predetermined minimal distance apart.
[0094] Other characteristics and advantages of the invention will
be clearly highlighted by the description which is made of it,
thereafter, for information only and not in the least limitative,
by reference to the annexed drawings, wherein:
[0095] FIG. 1 represents a device of prior art comprising a
shearing unit moving by comparison with the main frame of the
device;
[0096] FIGS. 2a and 2b represent a device in accordance with the
invention respectively seen in back and front perspective;
[0097] FIG. 3 is a schematic side view of the device of the
invention according to a plane parallel to the axis of the sheet
metal strip running while the sheet metals are running in the
joining device;
[0098] FIGS. 4a, 4b, 4c, 4d, 4e, 4f, 5a and 5b are representing
successively the chronological steps implemented by the device of
the invention to join two disjointed sheet metal strips;
[0099] FIG. 6 is a schematic representation of a gooseneck-shaped
shearing unit and of a shearing unit of the shearing press type
comprising two posts in fixed relation with the frame, as well as
drawings that show the stresses and the sweeps during the sheet
metal cutting for each one of these shearing units, this figure
demonstrating the advantage of the shearing press in comparison to
a gooseneck-shaped shearing apparatus.
[0100] As announced before, the invention relates to a joining
device 0 for Laser weld joining sheet metal strips B after having
cut the ends Bt and Bq.
[0101] The device of the invention as represented in FIGS. 2a to 3
comprises a main frame 1 fixed on the ground and comprising a
platform 11, two posts 12 parallel to one another and inter-locked
by a beam 13 and a lower shearing frame 14 equipped with its two
lower blades 141a, 141b. The lower shearing frame 14 is adapted to
enable to make the clearance of the two lower blades vary in order
to allow an adjustment of the blade clearance for each lower and
upper pair of blades. To that purpose, parts of the frame are
mounted on guides parallel to the axis of the sheet metal strip
running.
[0102] The two posts 12 are carrying each a system of vertical
guides 121 that are receiving an upper shearing frame 2 and its two
blades 21a and 21b. The upper shearing frame 2 is operated
vertically by shearing jacks 22 supported by the beam 13.
[0103] The shearing unit C of the device of the invention comprises
the upper blades 21a, 21b and lower blades 141a, 141b as well as a
joint structure 6 to link together the upper and lower blades, this
joint structure 6 comprising the posts 12. This joint structure is
in fixed relation with the frame 1 and extends around the axis A of
sheet metal strip running. Thus, this structure 6 is particularly
rigid and symmetrical by comparison with the running axis A. The
upper blades are mounted fixedly on a blades holder in order for
the clearance between the upper blades to remain constant during a
cutting and so as to balance the cutting stresses. The upper blades
holder is adapted to enable the passing of a Laser welding head 4
between this upper blades holder and the lower blades at least when
the upper blades holder is away from the lower blades as it is the
case on FIG. 3. On this FIG. 3, it shows that the welding head 4
has room enabling it to do welding in the very heart of the
shearing unit when the lower and upper blades are away from one
another. This characteristic enables a great positioning and
welding precision as well as a saving of time in the sequence
between the operations of shearing and then of welding.
[0104] It should be noted that whichever the blade clearance is
chosen, the device of the invention is designed so as the blades
are always parallel to one another.
[0105] This parallelism ensures that the edges of sheared strips
are parallel themselves.
[0106] In order to enable the complete automatization of the
joining operation, a device implementing, for example, precision
screw jack ensures the moving of the upper blades or preferably of
the lower blades in the direction of an increase or of a reduction
of the shearing blade clearance according to the data of the
product, that is to say the data specific to the sheet metals to
cut (type of steel, thickness . . . ). These data are coming from
primary data noted PDI standing for "Primary Data Input" input in
the automatism of the conveyer line comprising the device of the
invention. An electronic system of clearance control can enable to
control the precision screw jacks in order to make the shearing
clearance vary according to the need.
[0107] On the main frame 1 are fixed sets of clamps 3 comprising a
first clamp 3a and a second clamp 3b.
[0108] Each of the clamps 3a, 3b ensures the prehension and the
moving of an end of a strip to weld B thus enabling to hold each of
the strips to weld in a dedicated clamp 3a, 3b. These clamps are
disposed on both sides of the space wherein can slide the blades
and the welding head 4.
[0109] The frame 1 also supports a system of horizontal guides 41
perpendicular to the direction of running of the strip B. These
guides are extending laterally outside the frame 1. This extension
is supported by a structure 42.
[0110] As it particularly shows on FIG. 5a, the system of guides 41
supports the gooseneck-shaped bracket 43 of the welding head 44,
said bracket 43 moves on the guides 41 from its rest position under
the structure 42 until it enters completely under the posts 12 of
the main frame 1 in order to do the welding of the two ends of
strips B held by the sets of clamps 3. On this FIG. 5b, it shows
that the upper blade 21a and lower blade 141a are away from one
another to enable the sliding of the welding head 44 that makes the
welding.
[0111] The beam of Laser welding is generated by a fixed generator
45 (visible on FIGS. 2a and 2b) located at the end of the structure
42 in a parallel or perpendicularly to it. Said Laser beam is
directed to the welding head 44 by an optical path 46 made of
mirrors.
[0112] The frame 1 also supports a system 5 of recovery and of
removal of the scraps from the sheared strips, this system being
particularly visible on FIGS. 2a and 4d.
[0113] The joining device 0 of the invention can be equipped with
pre-heating devices of the edges to weld as well as with devices of
post-heating or of thermal processing of the weld.
[0114] Control devices of the quality of the welded butt joint
during its making can also complete the joining device 0.
[0115] According to FIG. 3, one can see the device of the invention
while it is in the phase of running of the strip B in the conveyer
line, off welding operation (with the welding head away from the
inter-blades gap):
[0116] The clamps 3a and 3b are at the level of the conveyer line
Ld and their claws 31s and 31i are in spaced relation with one
another in order to give free way to the strip B.
[0117] The upper shearing frame 2 is in completely raised position
in its guides 121.
[0118] The goose-shaped frame 43 of the welding unit 4 is in
position of rest.
[0119] The retractable stop 32 is in down position.
[0120] According to FIG. 4a, the strip tail Bq and the head Bt of
the following strip are in the joining unit so as to be joined in
it.
[0121] The retractable stop 32 is first set in up position and the
devices of centring and of guiding of strip B of the transformation
line upstream and downstream of the welding unit position the strip
tail Bq and the head Bt of the other strip respectively resting of
the sides 32b and 32a of the stop 32. The claws 31s and 31i of the
claws 3a and 3b as well as the upper shearing frame 2 remain in
their position of origin, that is to say away from the sheet metal
strips. The gooseneck-shaped frame 43 of the welding unit 4 is
always in position of rest.
[0122] According to FIG. 4b, the claws 31s and 31i of the clamps 3a
and 3b are closing in to hold the two strip ends Bq and Bt.
Starting from this moment, the clamps are remaining held on the
strip ends in order to immobilize them in the clamps and this until
the welding operation is finished (the welding operation appears on
FIGS. 5a and 5b). The retractable stop 32 is going back down in
down position and is moving away from the sheet metals.
[0123] According to FIG. 4c, the clamps 3a and 3b are going down in
position of shearing at the level of the fixed blades 141a and 141b
until the contact of the lower claws 31i with the stops 33a and
33b. Advantageously, all or part of these stops can be adjusted in
height so as to ease the original adjustment of the machine.
[0124] According to FIG. 4d, the upper shearing frame 2 is pushed
downward by the shearing jacks 22, the upper blades 21a and 21b in
collaboration with the lower blades 141a and 141c shearing the ends
Bq and Bt of the strips. The shearing scraps Bcq and Bct are
recovered by the removal system 5.
[0125] According to FIG. 4e, after going back up of the upper
shearing frame 2 and thus of the upper blades, the clamps 3a and 3b
are vertically transporting the ends Bq and Bt of the strips until
the contact with upper stops 34a and 34b at the level of the
welding plane Ps. Advantageously, all or part of these stops can be
adjustable in height so as to ease the original adjustment of the
machine.
[0126] According to FIG. 4f, the clamps 3a and 3b are transporting
horizontally the ends Bq and Bt of the strips while staying at the
level of the welding plane Ps. A slaved moving system 36a and 36b
ensures the relative positioning of the strip ends Bq and Bt in the
position required for the Laser welding by taking in account
certain parameters issued from data known as PDI such as the
thickness of the strips and the extra thickness or under-thickness
that is looked for.
[0127] A management process of the extra thickness of the Laser
welds applicable with the device of the present invention is
described in the patent document EP 1 591 190. It takes into
account inaccuracies of shearing and of horizontal moving of the
clamps 3a and 3b.
[0128] The ends Bt and Bq of strips being in required position,
that is to say aligned in a parallel to the guides 41, the welding
head 44 then provides the joining by welding.
[0129] In a variation of embodiment, only one of the two clamps 3a
or 3b is positioned horizontally thanks to the slaved moving system
36a, 36b, the other clamp is closing in to contact side stops 35.
Advantageously, all or part of these stops can be adjustable in
order to ease the adjustment of the machine.
[0130] The presence and the combined use of the sets of stops 33,
34, possibly 35 and of the retractable stop 32 as well as the
implementation of the process of automatic adjustment of the gap
between the edges to weld thanks to device 36a, 36b enable a
precise, quick and repetitive positioning of the heads and tails of
the strips to join. The positioning quality of the edges to weld is
perfectly adapted to the requirements of a Laser welding and the
times concerning the welding are considerably reduced, thus
decreasing the costs of strip accumulation.
[0131] According to FIG. 5a, the gooseneck-shaped frame 43 carrying
the welding head 44 and guided by the guides 41 is making move said
welding head above the ends Bq and Bt to weld due to the effect of
its moving device 47. The Laser beam is initiated on the edge of
the ends of the strips and is remaining along the whole width of
the strips to weld. Advantageously, two rolls 49 located
immediately behind the welding head and along the axis of the
welded butt joint can forge a possible extra thickness of said butt
joint.
[0132] According to FIG. 5b, two guide rollers 48 operated by a
hydraulic or pneumatic jack and located just under the welding head
44 are producing an additional clamping of the upper side of the
ends Bq and Bt on the lower side of claws 31s.
* * * * *